High-resolution laser photoionization, photoelectron, and photodissociation studies of state-selected transition metal-hydrides, carbides, nitrides, and oxides

在这项由实验物理化学计划资助的项目中，加州大学戴维斯分校的吴卓耀教授和他的研究小组将测量双原子分子MX及其阳离子MX+的电离能、键离解能、振动和转动常数，其中M是3D过渡金属(M=Sc、Ti、V、Cr、Fe、Co、Ni或Cu)，X是主要的非金属基团(X=H、C、N或O)。一般的实验策略利用了这样一个事实，即大多数MX物种都具有长寿命的低电子状态，这允许应用各种双重共振技术(初始可见激发，然后是光电离、光电子或光解离)，这些技术可以绕过由于杂质物种引起的光谱拥塞或信号的正常问题。光解研究将涉及一种双色速度图离子成像方法，这不仅可以准确地确定MX的离解能，而且可以准确地确定各种离解通道的分支比。除了与含有过渡金属的双原子分子有关的具体问题外，在这个研究项目中开发的技术将在物理化学、天体化学和几乎任何其他需要精确光谱和离解能信息的化学领域产生重要影响。该研究项目还将为培训学生和博士后研究人员提供一个极好的工具，他们本身可能会继续开发基于激光的新技术。最后，吴教授是加州大学戴维斯分校针对少数族裔学生的本科研究项目(MORE/CAMP/MURPPS)的参与者。

In this project funded by the Experimental Physical Chemistry Program, Professor Cheuk-Yiu Ng of the University of California, Davis, and his research group will measure the ionization energies, bond dissociation energies, and vibrational and rotational constants of diatomic molecules MX and their cations MX+, where M is a 3d transition metal (M = Sc, Ti, V, Cr, Fe, Co, Ni or Cu) and X is a main group non-metal (X = H, C, N, or O). The general experimental strategy takes advantage of the fact that most MX species possess long-lived, low-lying electronic states that allow a variety of double resonance techniques (initial visible excitation followed by photoionization, photoelectron, or photodissociation) to be applied which can circumvent the normal problems of spectral congestion or signals due to impurity species. Photodissociation studies will involve a two-color velocity-mapped ion-imaging method, which should make it possible to determine accurately not only MX dissociation energies, but the branching ratios of the various dissociation channels.Beyond the specific questions related to diatomic molecules containing transition metals, the techniques developed during this research project will have important impacts in other areas of physical chemistry, astrochemistry, and virtually any other chemical science arena where precise spectral and dissociation energy information is needed. This research project will also provide an excellent vehicle for the training of students and post-doctoral researchers who themselves may go on to develop novel laser based techniques. Finally, Prof. Ng is a participant in the undergraduate research program (MORE/CAMP/MURPPS) for underrepresented minority students at UC Davis.